Pericardial Tamponade as a Late Symptom of an Apparently Stable Tumor

Introduction

Tumors of the mediastinum are often found incidentally on routine diagnosis. About 20 - 30 % of the mediastinal masses in adults are thymomas [[2]]. These slow growing tumors are divided into three distinct groups: nonmalignant thymomas (80 %); thymomas with some malignant characteristics such as invasive growth; and malignant thymic carcinomas (the latter two groups constituting 20 % of cases according to [[3]]). Thymomas are known for a high coincidence of paraneoplastic diseases such as myasthenia gravis (15 %) [[4]], but complaints such as pericardial effusion may also occur.

Since many years, the staging of these lesions has been carried out on the basis of Masaoka's classification ([[5]], [Table 1]), which lists prognostic factors for overall survival. The WHO has also published a histological classification ([[4]], [Table 2]), in which clinical outcome is associated with histomorphological signs. Stage I and II thymomas have been further differentiated according to their different prognosis based on their tendency to invasive growth.

Table 1 Masaoka classification of thymomas [5] Stage Characteristic features Incidence I Tumor encapsulated, no invasion 21 % II A Macroscopic invasion B Microscopic invasion 26 % III Invasion of pericardium, great vessels or lung 43 % IV A Pleural/pericardial dissemination B Metastases 7 % 3 %

Table 2 WHO classification of thymomas [4] Type Histological feature Incidence A Spindle-shaped or oval epithelial cells 4 - 7 % AB Type A mixed with lymphocyte-rich areas 28 - 34 % B1 Predominantly lymphocyte-rich. Small epithelial cells with few signs of atypia 9 - 20 % B2 Predominantly lymphocyte-rich. Polygonal epithelial cells with more signs of atypia 20 - 36 % B3 Predominantly eosinophilic epithelial cells with minor lymphocyte parts 10 - 14 % C Thymic carcinoma 7 %

Although there are reports of pericardial tamponade resulting from a benign thymoma [[5]], we report on a patient with symptomatic pericardial effusion from a benign thymoma which was known to be present for more than 20 years without any tendency to growth.

References

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